This invention relates to an anchor device which makes it possible to fasten a member or instrument to a surface of a wall to the back of which hands cannot reach.
For example, in order to fasten a member or instrument with a bolt to e.g. a wall surface in which it is impossible to form a threaded hole, it is necessary to position a nut on the back of the wall surface.
Thus, if it is impossible to insert a hand to the back of a wall, an anchor device is used which makes it possible to position a nut on the back of the wall surface by inserting it from the front surface of the wall surface.
A conventional anchor device is shown in U.S. Pat. No. 4,079,655 in which a wing-shaped nut formed by pressing a thin metal plate is held by an arm member that can be folded in two. The arm member, which has been folded in two, is inserted into a hole formed in a wall member from its front side with the nut threaded on a bolt, and the bolt is threaded with the arm member opened on the back of the wall member.
Such an anchor device has a problem in that because the wing-shaped nut is thin in wall thickness and weak in strength, deformation or breakage tends to occur due to loads. Thus, strong fastening is impossible and the structure is complicated, which increases the manufacturing cost.
Structurally, there was a problem that since it is necessary to form a hole that is fairly large in diameter compared to the outer diameter of the bolt in the wall member, according to the size of an instrument to be mounted, it was impossible to use such a conventional anchor device.
In order to solve these problems, the present inventor proposed an anchor device in which a bag-like portion is provided at the tip of a trough-like portion through a bendable portion, a metallic plate nut is inserted in the bag-like portion and a seating member is fitted on the trough-like trunk portion so as to be able to be retained. However, if the retaining state between the trough-like trunk portion and the seating member is made more stiff, in other words, the seating member is made less likely to come out, there arises a problem that resistance when the seating member is inserted increases, so that workability is lowered. Besides, there is an object of making a hole formed in a wall member as small as possible.
An object of this invention is to provide an anchor device which uses a nut that is thick in wall thickness, which permits strong fastening, which is simple in structure and low in the manufacturing cost, and which has improved workability.
According to a first aspect this invention, there is provided an anchor device comprising an inserting member having a trough-like trunk portion and a bag-like portion provided at the tip of the trough-like trunk portion through a bendable portion, the bag-like portion extending in a direction perpendicular to the axis of the trough-like trunk portion, a nut inserted in the bag-like portion and having a threaded hole in a portion protruding from the bag-like portion, a ring-shaped seating member fitted on the trough-like trunk portion, and retaining means for retaining the seating member so as not to come out of the trough-like trunk portion, the retaining means comprising a plurality of serrations formed on the trough-like trunk portion continuously in the longitudinal direction on both edges of the outer periphery of the trough-like trunk portion and a protrusion formed on the inner periphery of the seating member so as to contact with both edges of the trough-like trunk portion.
In a second aspect of the invention, there is provided an anchor device according to the first aspect of the invention characterized in that near the bottom of the outer periphery of the trough-like trunk portion, a thin deflecting portion is provided so as to extend in a longitudinal direction.
In a third aspect of the invention, there is provided an anchor device according to the first or second aspect of the present invention, wherein said nut has a substantially semicircular section, and the bag-like portion has a semicircular hole to receive the nut, and has a side facing the bendable portion, and the side face is a flat surface.